This invention relates to a process for making a balloon to be used as an attachment on the end of an endoscope used medically for observing, diagnosing and curing diseased parts of blood vessels or other internal tubular organs of human bodies, or which is used on the end of catheter for encasing the endoscope thereby protecting it from any disease polluted blood.
Conventionally, as disclosed in Japanese patent application No. sho 61-259595, a conventional process for making a balloon was disclosed in that a dipping former was dipped into a basic material (main raw material) comprising: a desired amount of colloidal sulfur type vulcanizing agent and the like; a zinc oxide type activator and the like; a dithiocarbamate type vulcanization accelerator; and a paraffin emulsion type anti-oxidant and the like, wherein a balloon shape film adhered around the forming mold was heated in vulcanizing oven.
The endoscope was generally used by inserting it into the blood vessel or internal organ for observing and diagnosing the above interiors by lighting a light-guide equipped on the end of endoscope, and then used for curing the diseased part by an effective surgery such as irradiation of Nd-YAG laser, argon (Ar) laser and the like. In the circumstances, in order to use the balloon for the above purposes, it was naturally required to provide a balloon having a good transparency.
In the above conventional process for making the balloon, however, a problem was that the conventional process had a trend to inferior transparency due to the use of admixtures such as vulcanizing agent and the like as mentioned in the above, therefore, it had to reduce the used amount of admixture if it was wished to improve the transparency. This was a contradiction because to reduce the amount of admixture was to reduce the tensile strength of film, therefore, it was compromised to maintain both transparency and tensile strength by thickening the thickness of film containing a amount of admixtures. However, an important purpose of the use of balloon in endoscope surgery, was to stop blood flow within a blood vessel by inflating the balloon to block up the passage closely. In this purpose, the conventional type balloon did not meet the above purpose and requirements.